I received a quote for dense pack cellulose for in the wall for $1.65 per square foot and a quote or urethane at $0.70 a square foot. Obviously the urethane is cheaper but will it perform as good as the cellulose? And is there a quick test to determine that the cellulose was applied at the correct density?

"Obviously the urethane is cheaper"
It's not obvious to me at all, and would be highly unusual. We see prices of .25-.35 per board foot for dense packed cellulose, and 1.00 +/- for closed cell spray foam. If the dense packed cellulose was priced as per SF of 5-1/2" wall, that equals .30/BF which is right in the ball park. I would expect that the .70 is also a board foot price - (1 SF @ 1" thick) not a square foot price, so with a 5-1/2" wall you'd be looking at 5.5X.70=$3.85/SF of wall. The installer should know how many bags he'll need to properly fill the wall to the correct density, so a simple count of bags used will give them a good idea. Press on the insulated wall with a closed fist - a properly dense packed wall will feel very firm.

Bob: That's probably half pound open cell polyurethane, not closed cell.

Also, very few homes in Florida are framed with 2x6- it's almost all 2x4. Still 3.5 board feet for 70 cents would be 20 cents/board foot, which is only 2/3 amount of the all-time lowest I've ever seen it quoted in my neighborhood.

Both dense packed cellulose and half pound foam are in the R13 range @ 3.5". The half-pound foam will be slightly more air tight. The labor content of dense packed cellulose is quite a bit higher than open cell foam or damp-sprayed cellulose, and usually comes in a bit higher than o.c. foam, but rarely 2x the cost. The $1.65 per square foot for 2x4 dense pack is a bit high. Even though it's sometimes cheaper than that for 2x6 construction it would still be a good price for 2x6, but on the expensive side for 2x4. If the interior walls have been gutted (and if you can spray foam, I'm assuming that's the case) damp spraying is probably going to be more competitive, but may still be more expensive than 20 cents/board foot foam.

Both dense packed cellulose and half pound foam are in the R13 range @ 3.5"

In other words, don't get swindled with the not-unheard-of "our foam is so effective that you only need 2".

Posted By jonr on 17 May 2016 09:33 PM

Both dense packed cellulose and half pound foam are in the R13 range @ 3.5"

In other words, don't get swindled with the not-unheard-of "our foam is so effective that you only need 2".

That's akin to "...but this amplifier is better, it goes higher than 10, all the way to  11..." , isn't it?  

With some closed cell foam you can indeed hit R13 @ 2",  but the shorter  2" thermal bridge through the framing is then much more severe, yielding significantly lower overall performance than 3.5" of open cell foam.

The quotes, if they were provided by reputable insulation contractors, should provide a lot more information than a $/sf number and the name of a material. The FTC require a lot more information for people selling insulation. If they aren't meeting that requirement, I'm not sure you want to work with them at all.

The FTC is something of a paper tiger when it comes to R-value claims enforcement, even when dealing with the manufacturers.

I've never (ever) heard of the FTC going after a mere installer/contractor.

The "...you only really need..." line o' bull is pretty common lore among installers, many of whom actually believe it. Some inspectors have even bought into the concept.

Correction, the foam product was $1/ square foot. At least that was what the person on the phone said. They use foam from the Deilec Company. The companies website said closed cell is used for warm climate while the open cell is for cold climates. Their top selling product is Sealection 500. They have a product called Agribalance that has a R-value of 4.45 vs. 3.8 for the Sealection 500. I would prefer to use the Agribalance product since I have worked with farmers for over 35 years. Has anyone used these products? And is open cell foam in fact recommended for hot-humid climates like Florida?

It's still not clear what thickness is being quoted.

The person I talked to mentioned shaving off the excess. Therefore I assume 3 1/2".

Many spray foam companies twist the truth and claim that their foam will "perform like...." but in reality R-Value is R-Value when it comes to spray foam. Theses companies will say that it's R-Value is "X" but will perform like "Y". That is borderline against the law with the FTC.The way they get around it is that they state the TRUE R-Value as "X" and play games with the other "Y" value.

Most companies do this with roof spray foam and will make claims with the open spray foam and state that 5" of open spray foam is R-20 but will perform like R-40. The reality is that the roof is R-20 and performs like R-20 and performs worse than code R-40 roofs.

On the other hand, if someone is offering open-cell foam for less $/R than you can find any type of cellulose, then I'd take it.

Posted By agagent3 on 21 May 2016 01:04 PM
Correction, the foam product was $1/ square foot. At least that was what the person on the phone said. They use foam from the Deilec Company. The companies website said closed cell is used for warm climate while the open cell is for cold climates. Their top selling product is Sealection 500. They have a product called Agribalance that has a R-value of 4.45 vs. 3.8 for the Sealection 500. I would prefer to use the Agribalance product since I have worked with farmers for over 35 years. Has anyone used these products? And is open cell foam in fact recommended for hot-humid climates like Florida?

The alleged website assertion is utter crap. Open cell foam in cold climates requires a separate vapor retarder to protect the sheathing from taking on moisture in winter from interior moisture drives, whereas closed cell foam by itself is a sufficient vapor retarder.

Open cell foam is just fine in hot humid climates like FL.

Agribalance is 0.7lbs per cubic foot density, whereas Sealection 500 is 0.5lbs.  When installed between studs I wouldn't pay any extra for the 0.7lb goods.  At a 25% framing fraction the difference in "whole wall" performance between R3.8/inch and R4.45/inch in a 3.5" stud bay is about R0.44, not even R0.5.  But if it's only 5% more, the "extra" R0.44 is about 5% more whole-wall performance, so why not?

The agriculturally derived chemical in Agribalance is a mere 15-30% of just the B-side component, that's it. No matter how much they try to greenwash it, it's substantially the same poop with a couple of leafy greens thrown on top.  Both are blown with water instead of HFCs  (used in most closed cell foam.) 

Demilec is going to transfer over to HFO blown closed cell foam soon (as LaPolla already has), but they haven't announced the date.  When they do make the switch it will dramatically reduce the greenhouse gas footprint of their closed cell foam, but it's still has substantial polymer per R issue.  Like the 0.7lb foam vs. 0.5lb foam, it doesn't buy enough performance when installed between framing to be worth the up-charge, OR the environmental hit.   But closed cell is worthwhile in places where the low vapor permeance becomes an asset rather than a liability (say, on a crawlspace foundation wall.)